Hi:
   Look for Bheringer C2. That's a matched pair of stereo mics. They are much better than they deserve to be at the price. Aim one at the 12th. fret and the other, lower down on the guitar.
AKG makes an excellent, affordable 1" condenser mic., the AKG Perception 100 or 200.
Mind you, I would record guitar and vocals at the same time. You can use them as ghost tracks or keep them, depending on your performance.
I had an Alesis but couldn't get it to work with Vista. Had inserts and Pad switches if I remember correctly.
Turn the recording level down to an acceptable level on your Alesis. This will get rid of the booming and other distortions. Look at your wave pattern. It should stay comfortably within the lines.
3" from the vocal mic and use a Pop Filter. Same rules apply for volume levels. Stay well within the lines. Turn the channel down on the Alesis to achieve this.
Once you have recorded a good, clean sound then and only then, should you be starting to add effects, E.Q>, Reverb etc..
Now, TINKER!
Cheers!
Jim